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Cam question.

  • Thread starter Thread starter Guest
  • Start date Start date
Ah, yes, when I suggested GSXR cams I forgot the center cylinders of a four are in step and the twin not so much...
It is possible to cut and reindex the cams in the correct relation - but the cams are chilled cast iron so present a welding problem...
Some tricky machining to put a spigot through the joint then pin the spigot would also work but $$$ will come into it.
Get it running on the standard 400 cams then look at getting an aftermarket grind done. Picking up a spare set of standard cams would be worth doing too.
 
I've tried to do everything on spare parts and keep the originals.

I do have another set of original cams to play with And maybe a complete engine coming.

its good to have options, for now I'm sure the stock will be fine.
 
Have you looked into maybe 450 cams, or aftermarket? I'm kinda loosing the concept of "having" to cam a 400?

Though it would be pretty cool to be able to say "my 400 just smoked a 750". haha!
 
I'm kinda loosing the concept of "having" to cam a 400?
Click to expand...
I might have to cam a gs400 with a 78mm bore.

There is a problem with using the 450 cams having to do with the rocker offset.
 
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I am a dealer for Web Cams & Cam Motion & can get yours welded & reground to your specs. I can even recommend what would work well for yours as far as the grind profiles. Ray.
 
A guy named Mr. Riggs rephased an XS650 camshaft by doing the following:

RPcam03.jpg


RPcam06.jpg


RPcam07.jpg


RPcam08.jpg


RPcam09.jpg


RPcam13.jpg


RPcam14.jpg


I don't know how much meat there is on the camshaft you have to work with, but it's a pretty novel way to get the timing you need. Your rephase would be much simpler, since the XS cam was going from 360 degrees to 277 degrees. You would just be moving the lobes 180 degrees. If you needed more peace of mind I suppose you could also weld it, but cast iron is tricky to weld and you need someone with experience to know it won't get screwed up.
 
Why in the world would you go to that much trouble & time when there are cam grinders that have been doing this kind of stiff for so long?!!! Ray.
 
thays what i said ray, would be real easy to send it off for a custom grind/hard facing job

also, where is the sprocket going to bolt up? just wondering
 
Don't know if this helps, but I have my valve cover off of my '83 750T 16v right now
And the 2 inner lobes are 180 degrees of each other. Both exhaust and intake.
I'm not very knowledgeable on such mods yet. Hope it might be useful info for you.
 
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Thanks for looking Spyder. The idea was to use a 4 cylinder cam but because the center two are 180 degrees apart it will not be as easy as I originally hoped.

Mine are 90 degrees apart like your left or right 2 cylinders. It would be too much work (although possible with some creative thinking) to do when there are already easier ways to do it.

As Ray and platinum2 have pointed out I'm best off to have them welded and reground.
That's the way I'm going to go once I reach that point in the build.

.
 
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About my cam's, just for fun

intake lift 0.180" (4.5mm)
Rocker compensation lift (cam lift *1.55) 0.280" (7mm)


Just an interesting yet crazy thought:

If I put a gs450 cam having a lift of 0.280" in my head that would make an effective valve lift of 0.434" (10.85mm)

A bid much :p


Spyder said:
Have you looked into maybe 450 cam.
Click to expand...

I didn't quite answer why before so this is one reason reason why it wouldn't be as simple as that for my application.
 
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Mekanix said:
About my cam's, just for fun

intake lift 0.180" (4.5mm)
Rocker compensation lift (cam lift *1.55) 0.280" (7mm)


Just an interesting yet crazy thought:

If I put a gs450 cam having a lift of 0.280" in my head that would make an effective valve lift of 0.434" (10.85mm)

A bid much :p




I didn't quite answer why before so this the real reason why it wouldn't be as simple as that.
Click to expand...


Well no - that sort of lift can be accomodated in full out race motors....the real reason you can't use 450 cams - or 2V 400, or 425 cams is that all the bucket and shim cams use symmetrical profiles and yours HAS to use an assymetric profile, It uses an assymetric profile to get symmetrical lift and fall rates with the rockers....
 
GregT said:
Well no - that sort of lift can be accommodated in full out race motors....the real reason you can't use 450 cams - or 2V 400, or 425 cams is that all the bucket and shim cams use symmetrical profiles and yours HAS to use an asymmetric profile, It uses an asymmetric profile to get symmetrical lift and fall rates with the rockers....
Click to expand...


Ok, my bad, I only meant it was too much for my application.

I had to research it and see it for myself but I get it now:o
 
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